Reciprocating air motors of the type used to drive reciprocating piston pumps and the like have been well known for many years. One problem with such products has been that when operating continuously in humid air, the condensation which forms in the exhaust of the air motor and the air valve tends to form ice which can eventually lead to slowing or indeed complete stopping of the pump. The pump is then out of action until the ice is thawed, hopefully through a high enough ambient temperature.
Various efforts have been made to reduce such icing and toward that end, my prior U.S. Pat. No. 4,921,408 and my currently pending U.S. Pat. application Ser. No. 07/904,447, filed Jun. 25, 1992, show ways of greatly reducing this problem. The techniques shown in the aforementioned patent and application (the contents which are hereby incorporated by reference) are not always entirely effective, particularly when the passage through which the exhaust travels is located such that it is difficult to apply heat to it by the known methods.